This invention relates to novel shaped cleansing compositions such as bars or cakes of enhanced performance qualities in which at least a portion of the composition is comprised of a synthetic surface active ingredient.
Although widely used for over a century, fatty acid soaps are known to possess certain shortcomings. For one thing, fatty acid soaps are inefficient cleaning agents, in that, in aqueous systems the surface tension of the soaps is higher than desired, and the grease-cutting efficiency of the soaps is inadequate. Moreover, fatty acid soaps have very poor tolerance to hard water, and thus produce little if any suds and form soap scums when used with hard water.
Over the years, numerous attempts have been made to circumvent the foregoing deficiencies of the fatty acid soaps by utilization of synthetic surface active ingredients in the manufacture of so-called xe2x80x9csyndetxe2x80x9d bars composed entirely of synthetic surface active ingredients, and xe2x80x9ccomboxe2x80x9d bars composed in part of synthetic surface active ingredients and in part of the fatty acid soap. Although these approaches have overcome many of the shortcomings of fatty acid soaps, the use of syndet and combo bars has given rise to new shortcomings. Among such shortcomings are unacceptable slough rates, harshness to skin, and loss of structural integrity during use. Also, in many cases the costs associated with production of syndet bars or combo bars are higher than desirable. Consequently, there remains a need for soaps comprised of one or more synthetic surface active ingredients with superior performance qualities which can be achieved at relatively modest costs.
This invention is deemed to fulfill the foregoing need in a highly efficient manner.
U.S. Pat. No. 4,277,378 describes an alkaline builder-free detergent composition containing a partially neutralized succinic acid derivative in which the succinic acid moiety is substituted by a saturated or unsaturated hydrocarbon group having 8-18 carbon atoms, such as an alkenyl group that can be branched or straight chain. In Examples 7 and 8 syndet bars were made from formulations containing partially neutralized di- or triethanolamine salts of tetradecenyl succinic acid. These bars are reported to have excellent foaming properties and to be comfortable when used.
Test work performed in our laboratories, indicates that fully neutralized triethanolamine salts of straight chain alkyl or alkenyl succinic acids are tacky substances.
Pursuant to this invention, it has been found possible to provide cleansing bars comprised of one or more particular surface active ingredients, which bars have a number of superior performance qualities. Moreover, these advantages can be achieved with materials that can be readily produced from readily-available raw materials at relatively modest costs.
This invention provides in one of its embodiments a cleansing bar comprised of at least one fully neutralized alkali metal salt of an alkyl or alkenyl succinic acid in which the alkyl or alkenyl group is a straight chain alkyl or alkenyl group containing in the range of about 8 to about 14 carbon atoms. The sodium and potassium salts are preferred, with the sodium salt being most preferred. Unlike the fully neutralized triethanolamine salts, the fully neutralized alkali metal succinate salts, especially the fully neutralized sodium salts, are completely free of tackiness.
The cleansing bars of this invention on an anhydrous basis will typically comprise in the range of about 5 to 100 wt %, and preferably in the range of about 10 to 100 wt % of one or more of the alkyl and/or alkenyl succinic acid salts (often referred to hereinafter collectively as xe2x80x9calk(en)yl succinic acid saltsxe2x80x9d). Typically, the cleansing bars of this invention will contain up to about 15 wt % of water, either as free water or as water of hydration, or both.
The alk(en)yl succinic acid salts used pursuant to this invention are white, high-melting solids which at room temperature are highly-crystalline whereas at mildly elevated temperatures often used in preparation of commercial cleansing bars (e.g., 50-80xc2x0 C.) can be easily compounded with other ingredients (if desired) and shaped into the desired form. Moreover, when in the form of bars or cakes, such alk(en)yl succinic acid salts have considerable structural integrity at room temperature. In addition, such bars or cakes exhibit excellent lathering in all types of water, low wear rates, good tactile properties, minimal slushing and curd-forming properties in all types of water, and mildness to the user""s skin. Further, such bars are resistant to becoming mushy and susceptible to excessive sloughing upon standing in a soap dish in contact with water.
Other ingredients can be included in the cleansing bars and cakes of this invention. By way of example, depending upon the intended use of the bar or cake, there may be combined therewith one or more other types of surfactants, including known anionic, nonionic, zwitterionic, or amphoteric surfactants, as well as one or more conventional fatty acid soaps. In this connection, the most important fatty acid based compositions that may be used as the soap base in the bars or cakes of this invention are stearic acid, coco fatty acids, and tallow fatty acids, as well as mixtures of these fatty acids. Such fatty acids can be fully or partially hydrogenated. The more common of these mixtures are those containing tallow:coco fatty acid ratios of 80:20, 85:15, 70:30 and 50:50, with tallow:coco fatty acid ratios of 80:20 and 85:15 being the most common.
The soap bars of this invention may also contain about 3 to about 15 wt %, and more preferably about 4 to about 6 wt %, glycerine. Superfatting agents may also be used in the soap bars of this invention. These superfatting agents include unneutralized fatty acids, fats, and oils and mineral oils. The fatty acids are the more preferred of such agents. The superfatting agents are preferably used in amounts of about 3 to about 6 wt %, but amounts of up to about 10 to about 15 wt % may also be used.
Other additives commonly employed in the soap bar-making arts may also be used in the soap bars of this invention, for example, colorants, such as TiO2, perfumes, stabilizers, bacteriostats (e.g., as deodorants or germicides), and processing aids such as common salts. All of these other additive materials are used at levels of up to about 1 wt %, except for perfumes which may be used at levels of up to about 2 to about 3 wt %.
If it is desired to include other surfactants in the cleansing bars of this invention, preferred surfactants for this purpose include alkali metal salts of acyl isethionates, fatty alcohol sulfates and alkane sulfonates, alone, or in the various admixtures thereof. Other surfactants that may be used include, for example, sodium lauryl sulfoacetate, fatty acid sarcosinates, sodium lauryl glyceryl sulfonate and sodium dodecyl benzene sulfonate. The surfactants are used in the cleansing bars of this invention at a level of about 15 to about 70 wt %, and preferably in the range of about 15 to about 20 wt %, based on a solids content basis.
Fillers that may be used in the syndet or combo bars of this invention are water-insoluble inorganic materials having an average particle size of about 0.05 to about 20 microns, and preferably of about 0.5 to about 5.0 microns. The fillers are preferably pretreated by being ground to achieve the desired particle size, if necessary, and/or they may be chemically-precipitated to provide a desired particle size.
Another advantageous feature of this invention is that the above-described cleansing bars and cakes can be produced using any one of the conventional soap-making techniques. Such techniques are well known to those skilled in the art and are reported in the literature. See for example U.S. Pat. No. 3,178,370 to Okenfuss, et al., and Berna et al., Journal of Surfactants and Detergents, Vol. 1, No. 2, pages 263-271 (April 1998).